In contrast to other recent Moscow protests, which have been broken up by massed ranks of riot police, Thursday's gathering of a few dozen activists was allowed to meet peacefully in the central Slavyanskaya Square.

The group's leader, Khimki businesswoman Yevgenia Chirikova, was permitted to deliver to Kremlin officials a petition urging Mr. Medvedev to stop the arrests of environmental activists and seizure of their newsletters by Khimki authorities and ensure that "honest" hearings on the issue are allowed to take place.

"We are facing a campaign of suppression, slander, and lies orchestrated by local authorities," Ms. Chirikova says. "We tried to explain our position in a special edition of our newspaper a few days ago, but police seized every copy. Nine of our activists, and two journalists, are currently in court and facing prison sentences just for speaking out about this issue."

Analysts say the controversy may be turning into a wedge between Prime Minister Vladimir Putin, who has sponsored the road project, and Medvedev, who has tried to project a more liberal image. The two have worked in tandem surprisingly well since Medvedev was inaugurated more than two years ago, though Mr. Putin has consistently appeared to be the stronger player.

But the moment is fast approaching when Kremlin power circles will have to decide which of them will run as the establishment's candidate in presidential polls in 2012, and that has led to an uptick in publicly expressed differences between them.

"It's hard to say there's any public break between Putin and Medvedev over the Khimki Forest," says Sergei Markov, a Kremlin-connected Duma deputy. "Medvedev shows more concern for public opinion, while Putin emphasizes the importance of economic development. These could be two sides of the same coin, but they have the potential for conflict."

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For the past several years, the environmentalist group, Defenders of the Khimki Forest, has been trying to mobilize opposition against plans to build a toll road between Moscow and St. Petersburg that would cut through the heart of the 1,000-hectare ancient woodland, part of a legally protected "green belt" around Moscow until it was removed from that status by decree of Putin a year ago.

Last April, the Supreme Court rejected a citizens' appeal to overturn the decree. But in mid-August, several thousand people rallied in downtown Moscow, including Russian rock star Yury Shevchuk, to support the Khimki activists. After U2 frontman Bono also raised the issue in a private Kremlin meeting with the president, Medvedev ordered the road-building project suspended pending a full review.

"Our people ... are saying [the clear cutting of Khimki Forest] demands more analysis," Medvedev said in his online video blog. He added that his decision had been prompted by the "high public resonance" the issue had attracted.

"The Khimki controversy accelerated very rapidly, and it made the authorities quite nervous. So they decided to make a pause," says Nikolai Petrov, an expert with the Carnegie Center in Moscow. "But public hearings are an easy thing to orchestrate, and the Khimki authorities have moved into action by organizing their own public meetings and petition campaigns. For example, they did a poll asking local residents whether they prefer the road to pass through the forest, or through their dachas, which naturally produced 'public support' for building it in the forest."

Local authorities, who stand to gain the most from privatizing a vast tract of real estate on the fringes of Moscow, have been accused of corruption by Chirikova's group, who say the official listed price of forest land of 4,300 rubles (about $140) per hectare is ridiculously low and an obvious cover for dishonest dealing.

Most analysts cautiously agree. "I think Khimki authorities are very much under the influence of corporations and other such interests," says Mr. Markov. "They want this project very much because they have probably included their private interests in the bigger calculations."

Medvedev reiterated his stand at an official forestry conference on Wednesday, saying that expert hearings were needed to decide whether alternative routes for the road might be viable. "This does not imply that economic considerations are sidelined, but we should take into account ecological factors as well when deciding the issue," he said.

This week, the forest route gained the support of powerful Moscow mayor Yury Luzhkov, whose billionaire wife is one of Russia's leading real estate developers. "The planned and agreed route should stay. It is realistic," Mr. Luzhkov wrote in the government newspaper Rossiskaya Gazeta. "Some sacrifices have been made, and it is a pity. But the price is more justified than the alternatives."

One of those proposed alternatives would have routed the road through the Moscow suburb of Molzhanivovo, where Luzkhov's wife, Yelena Baturina, owns land, says Mikhail Delyagin, director of the independent Institute of Globalization Problems in Moscow. "What we're seeing here is clan struggle, competing business interests" that have supporters at the highest levels of power, he says. "Lots of people have their fingers in this."

Some experts say the official hearings, set to open next week in Russia's Kremlin-guided Public Chamber, are mostly window dressing to make Medvedev look like he's been sensitive to environmental concerns while ultimately rubber-stamping the Putin plan.

"The Public Chamber will probably let the protesters speak and let off steam, but conclude in the end that the majority supports the road being built through the forest," says Carnegie's Mr. Petrov. "Medvedev's image will be polished, because he let the discussion continue for awhile longer."